Device for alignment of stock in a printing machine

ABSTRACT

It is a device for alignment of stock, such as a sheet of paper or a film, in the transport path of a printing machine, especially in the transport path between a storage container for the stock and the print station or the print station and finishing devices, such as stitching and binding devices and collecting or stacking containers.  
     The device consists of a cylindrical drum ( 11 ), with an axis ( 13 ) of rotation which is transverse to the transport path, and it has on one of its end faces a rotating stop edge ( 14 ) which projects vertically over the periphery of the drum, there being at least one alignment wheel ( 16 ) which is supported to be able to swivel, which rests on the circumference of the drum ( 11 ), and which has a line of action which can be aligned at an acute angle to the stop edge ( 14 ) by means of a controlling torque [(F con )].

[0001] The invention relates to a device for alignment of stock, such as a sheet of paper or a film, in the transport path of a printing machine, especially in the transport path between a storage container for the stock and the print station or the print station and finishing devices, such as stitching and binding devices and collecting or stacking containers.

[0002] In Patent Abstracts of Japan, JP 61-2642, a sheet alignment device for a copier is disclosed. A sheet is aligned with respect to a stop or a guide. A wheel attached to a swiveling arm touches the surface of the sheet which is to be aligned. A spring exerts a controlling torque on the swiveling arm, tilting the line of action of the wheel by a certain angle with respect to the stop. Consequently, a lateral force component [P₁] is exerted by the wheel on the sheet and transports the sheet in the direction of the stop. If the sheet is aligned, the lateral component [P₁] decreases and as a result the drive element swivels back to the stop, by which at this point the line of action of the wheel is parallel to the transport direction of the sheet.

[0003] Document EP-A-0 496 398 likewise discloses a sheet transport device for aligning a sheet with respect to an alignment edge. To do this, above the alignment edge a rotary axle which bears a transport roller is guided through a slot. A spring acts mechanically on the axle in the direction of the alignment edge, by which the transport roller assumes an angular position with respect to the alignment edge. When the sheet is aligned on the alignment edge, the axis of rotation of the drive wheel swivels back against spring force, by which the transport roller applies a force to the sheet only in the transport direction.

[0004] The disadvantages of the prior art are that when the stop is reached the drive rollers or drive wheels of the alignment device swivel back, but sliding or slipping of the drive element on the top of the sheet still occurs. This is especially deleterious for sensitive sheet surfaces or for thin sheets, since they can be damaged by the friction arising between the sheet and the drive element.

[0005] The object of the invention is to devise a device which has a simple, economical structure and which works reliably.

[0006] This is achieved as claimed in the invention by a device with the features as claimed in claim 1.

[0007] One such device compared to known devices has the advantage that the alignment process is not hindered by the forces of friction between the feed edge of the stock and edge of the stop because the stock and the feed edge move essentially with the same speed.

[0008] It is also a major advantage that the alignment process is not hindered by forces of friction between the stock and the sheet support surface, the drum surface, because the stock and the drum move likewise with the same speed.

[0009] Moreover it is advantageous that the stock when being aligned by its contact with the drum surface experiences arching perpendicular to the transport direction and parallel to the controlling torque [(F_(con))]; this imparts high stability to the stock. In this way even very thin stock can be transported and aligned reliably and safely.

[0010] In particular, the device is made such that the alignment wheel sits in a holding device and is pivotally mounted around a carrying axle which is parallel to the axis of the drum. The holding device for its part is mounted to be able to swivel around a pivot pin and a housing-mounted support and the pivot pin is located perpendicular to the surface of the drum and in the transport direction in front of the alignment wheel.

[0011] To produce the controlling torque [(F_(con))], on the pivot pin there is a cylinder spring which at the same time produces the compressive force for the alignment wheel on the peripheral surface of the drum.

[0012] In one preferred embodiment, in the transport direction there is at least one other alignment wheel, the distance of the two alignment wheels measured over the circumference of the drum being smaller than the length of the stock.

[0013] When wide stock is being transported, it is a good idea to arrange two alignment wheels at a time next to one another transversely to the transport direction and with a distance to one another.

[0014] The other features and advantages can be taken from the description of one embodiment of the invention and the other dependent claims.

[0015]FIG. 1 shows the device as claimed in the invention in a diagram,

[0016]FIG. 2 shows an alignment wheel of the device as shown in FIG. 1 in schematic form in a plan view,

[0017]FIG. 3 shows two successive alignment wheels of the device as shown in FIG. 1 in an enlarged diagram and

[0018]FIGS. 4a, 4 b, 4 c shows how the device as claimed in the invention works in a sequence of schematics.

[0019]FIG. 1 shows a device for transport and alignment of stock 12, such as sheets of paper, films or the like, during transport from one storage container to a print station or from a print station to finishing devices such as perforating, stitching or binding devices.

[0020] On one housing wall 10 a cylindrical drum 11 is pivotally mounted around an axis 13 of rotation which is located transversely to the transport direction of the stock 12. The drum 11 on the side of the housing wall has a vertically projecting, rotating stop edge 14 for the side edge of the stock 12. Downstream to an arrangement of feed rollers 15 there are one or two alignment wheels 16 which lie next to one another with an interval and which are attached to the housing wall 10 by means of a support 17.

[0021] The alignment wheel 16 is pivotally mounted in a holding device 18 around a carrying axle 19 which is parallel to the axis 13 of rotation of the drum 11. The holding device 18 is provided with a pivot pin 20 which is aligned perpendicular to the surface of the drum 11 and which is pivotally held in a bearing eye 21 of the support 17. Viewed in the transport direction, the alignment wheel 16 is behind the pivot pin 20. Around the pivot pin 20 there is a cylinder spring 22 which imparts elastic pre-tensioning to the alignment wheel 16 in the direction to the stop edge 14. The swiveling motion of the alignment wheel 16 by an angle a is limited by a projection 23 which is made on the pivot pin 20 and which comes into contact with the stop surface 24 which is provided on the support 17 in the end position of the alignment wheel. In this end position the line of action of the alignment wheel 16 is aligned at an acute angle to the stop edge 14. In this position the incoming stock 12 is moved by the alignment wheel 16 against the stop edge 14.

[0022] A pair of alignment wheels 16 which is located on the inlet side in this embodiment is series connected on the outlet side to another pair of alignment wheels 25. Here the distance of the alignment wheels 16 and 25 in the transport direction, measured on the circumference of the drum 11, is shorter that the length of the stock 12. In this way the stock has already been acquired by the alignment wheel 25 before it has left the alignment wheel 16; this leads to reliable alignment of the stock 12 on the stop edge 14. The alignment of the stock is however also ensured with a pair of alignment wheels which is located on the inlet side.

[0023] Finally, to guide the stock 12 on the drum 11 there is a flat guide body which is attached on the housing side, which is made segmented, and which is arranged concentrically to the axis 13 of rotation of the drum 11 and with a short distance to it. Another guide body 27 which consists of two segmented shells which are parallel to one another is downstream of the other alignment wheels 25. In the transport direction, between the stock 12 and the peripheral surface of the drum 11 no motion takes place and thus no friction either, which could lead to unwanted static charging of the stock.

[0024] The stock is aligned as possible.

[0025] The stock 12 supplied by the feed rollers 15 is acquired by the alignment wheel 16 and executes the alignment motion which is shown in FIGS. 4a, 4 b and 4 c. As long as the trailing end of the stock 12 is running between the feed rollers 15, the alignment wheel 16 is parallel to the transport direction and the stop edge 14 (see FIG. 4a). Only when the trailing end of the stock 12 leaves the feed rollers 15 does the controlling torque [F_(con)] take effect and the stock 12 is moved by the alignment wheel 16 which is positioned slanted by the angle [beta] as a result of the cylinder spring 22 as the axial friction is overcome (there is no friction in the transport direction) between the stock 12 and the peripheral surface of the drum 11 against the stop edge (see FIG. 4b). When the stock 12 with its entire lengthwise edge adjoins the stop edge, is therefore aligned, the alignment wheel is again set parallel to the transport direction against the force of the cylinder spring 22 (see FIG. 4c).

[0026] For long distances in the transport direction the alignment process of the first alignment wheel 16 is supported by the other alignment wheel 25. If the first alignment wheel 16 has already accomplished alignment of the stock, the other alignment wheel 25 undertakes stabilization of the aligned position of the stock 12.

[0027] After alignment of the stock has been completed, the alignment wheel 16, 25 or the alignment wheels swivel against the controlling torque [F_(con)] into a position parallel to the transport direction.

[0028] After the stock 12 has also left the other alignment wheels 25, it is delivered by the discharge rollers 28 to finishing. Reference number list 10 housing wall 11 drum 12 stock 13 axis of rotation (drum) 14 stop edge 15 feed rollers 16 alignment wheel 17 support 18 holding device 19 carrying axle (alignment wheel) 20 pivot pin (holding device) 21 bearing eye 22 cylinder spring 23 projection 24 stop surface 25 2nd alignment wheel 26 guide body 27 guide body 28 discharge rollers 

1. Device for alignment of stock, such as a sheet of paper or a film, in the transport path of a printing machine, especially in the transport path between a storage container for the stock and the print station or the print station and finishing devices, such as stitching and binding devices and collecting or stacking containers, wherein it has a drum (11), there being at least one alignment wheel (16, 25) which is supported to be able to swivel, which rests on the circumference of the drum (11), and which has a line of action which can be aligned at an acute angle to the stop edge (14) by means of a controlling torque [(F_(con))].
 2. Device as claimed in claim 1, wherein the alignment wheel (16; 25) sits in a holding device (18) and is pivotally mounted around a carrying axle (19) which is parallel to the axis (13) of rotation of the drum.
 3. Device as claimed in claim 2, wherein the holding device (18) can swivel around a pivot pin (20) in a housing-mounted support (17) and the pivot pin (20) is located perpendicular to the surface of the drum (11) and in the transport direction in front of the alignment wheel (16; 25).
 4. Device as claimed in one of claims 1 and 3, wherein to produce the controlling torque [(F_(con))], on the pivot pin (20) there is a cylinder spring (22) which at the same time produces the compressive force for the alignment wheel (16; 25) on the peripheral surface of the drum (11).
 5. Device as claimed in claims 1 to 4, wherein to limit the swiveling motion of the alignment wheel (16; 25) on the pivot pin (20) there is a projection (23) which interacts with the stop surface (24) which is made on the support (17).
 6. Device as claimed in claim 1, wherein in the transport direction there is at least one other alignment wheel (25), and wherein the distance of the two alignment wheels (16; 25) measured over the circumference of the drum (11) is smaller than the length of the stock (12).
 7. Device as claimed in claims 1 and 6, wherein in the transport direction the alignment wheel or the alignment wheels (16) are located in the area of the feed rollers (15) which are located in front of the drum (11) and the other alignment wheel or alignment wheels (25) are located in the area of the discharge rollers (28) which are located after the drum (11).
 8. Device as claimed in one of claims 1 to 7, wherein downstream of the respective alignment wheels (16; 25) are guide bodies (26 and 27) for the stock (12).
 9. Device as claimed in claim 8, wherein the guide body (26) which is located downstream of the alignment wheels (16) which are located on the inlet side consists of a flat arched shell which is located concentrically to the axis (13) of rotation of the drum and with a small distance to the drum circumference.
 10. Device as claimed in claims 1 to 9, wherein two alignment wheels (16 and 25) at a time are located next to one another transversely to the transport direction and with a distance to one another. 